High-low pressure dome type compressor

ABSTRACT

Formed in a scroll type compression mechanism is a connection passageway with a discharge opening through which refrigerant compressed by the compression mechanism flows out into a clearance space defined between the compression mechanism and a drive motor. A muffler space in communication with the connection passageway that is configured to reduce operating noise is formed in the compression mechanism. A motor cooling passageway configured to circulate working fluid which has flowed out into the clearance space is formed between the drive motor and an inner surface area of a casing. A guide plate is disposed in the clearance space. Formed in the guide plate is a flow dividing concave portion which causes a part of refrigerant flowing toward the motor cooling passageway to be distributed in a circumferential direction and toward an internal end of a discharge pipe located in the clearance space.

TECHNICAL FIELD

[0001] The present invention relates generally to high-low pressure dometype compressors. This invention pertains more particularly to measuresaimed at providing a compression mechanism with a simplifiedconstruction, and at making improvement in efficiency of cooling a drivemotor.

BACKGROUND ART

[0002] High-low pressure dome type compressors have been known in theprior art. For example, Japanese Patent Kokai Gazette No. (1995)310677discloses one such compressor in which its casing internal space isdivided into a high- and low-level pressure spaces facing each otheracross a compression mechanism and a drive motor drivingly connected tothe compression mechanism is disposed in the high-level pressure space.This type of high-low pressure dome type compressor is provided with aninternal discharge pipe for guiding working fluid compressed by thecompression mechanism to the high-level pressure space. And, a dischargepipe, through which refrigerant in the high-level pressure space isdischarged outside the casing, is connected to the casing. An outflowend of the internal discharge pipe is located in a clearance spacedefined between the compression mechanism and the drive motor.

PROBLEMS THAT INVENTION INTENDS TO SOLVE

[0003] However, a high-low pressure dome type compressor of theabove-described conventional type requires provision of such an internaldischarge pipe for guiding working fluid compressed by a compressionmechanism to a high-level pressure space. As a result of this, thenumber of component parts required increases and it is required that thecasing outside diameter be increased. Therefore, it is difficult toprovide a compressor with a compact construction.

[0004] Further, since it is arranged such that the outflow end of theinternal discharge pipe is located in a clearance space defined betweenthe compression mechanism and the drive motor, the working fluid failsto cool the drive motor at high efficiency.

[0005] On the other hand, in order to make improvement in capacity ofcooling a drive motor, it is conceivable that, instead of employing aninternal discharge pipe as described above, a working fluid passagewayis provided in the inside of a drive shaft so that working fluid isguided, through the working fluid passageway, to a lower space of thedrive motor. In this case, however, the drive shaft falls lower in itsrigidity and the level of operating nose is increased by shaft vibrationcaused by discharge pulsation. Furthermore, problems, such as anincrease in the number of processing steps of the drive shaft and anincrease in the number of sealing-related component parts, arise.

[0006] Bearing in mind the above-described problems with the prior arttechniques, the present invention was made. Accordingly, an object tothe present invention is to provide a high-low pressure dome typecompressor with a compact construction as well as to cool a drive motorat high efficiency.

DISCLOSURE OF INVENTION

[0007] In order to achieve the foregoing object, the present inventiondiscloses an arrangement in which a connection passageway (46), throughwhich working fluid compressed in a compression chamber (40) of acompression mechanism (15) flows out into a high-level pressure space(28), is formed in the compression mechanism (15), and working fluiddischarged from the connection passageway (46) circulates through amotor cooling passageway (55) formed between a drive motor (16) and aninner surface area of a casing (10).

[0008] More specifically, a first invention of the present applicationis directed to a high-low pressure dome type compressor in which aninternal space of a casing (10) is divided into a high- and low-levelpressure spaces (28) and (29) facing each other across a compressionmechanism (15) and a drive motor (16) drivingly connected to thecompression mechanism (15) is disposed in the high-level pressure space(28). In the high-low pressure dome type compressor of the firstinvention, a connection passageway (46), through which working fluidcompressed in a compression chamber (40) of the compression mechanism(15) flows out into a clearance space (18) defined between thecompression mechanism (15) and the drive motor (16), is formed in thecompression mechanism (15), and a motor cooling passageway (55), throughwhich working fluid which has flowed out of the connection passageway(46) circulates between the clearance space (18) and a side of the drivemotor (16) which is opposite to the compression mechanism (15), isformed between the drive motor (16) and an inner surface area of thecasing (10).

[0009] Further, in a second invention of the present applicationaccording to the first invention, the compression mechanism (15) isprovided with a muffler space (45) which is formed between thecompression chamber (40) for working fluid compression and theconnection passageway (46).

[0010] Furthermore, in a third invention of the present applicationaccording to either the first invention or the second invention, a guideplate (58), for guiding working fluid which has flowed out of theconnection passageway (46) to the motor cooling passageway (55), isdisposed in the clearance space (18).

[0011] Further, in a fourth invention of the present applicationaccording to the third invention, the casing (10) is provide with adischarge pipe (20) through which working fluid in the high-levelpressure space (28) is discharged outside the casing (10), and the guideplate (58) is provided with flow dividing means (90) for allowing a partof working fluid flowing toward the motor cooling passageway (55) to bedistributed in a circumferential direction and for guiding thedistributed working fluid to an internal end (36) of a discharge pipe(20) located in the clearance space (18).

[0012] Furthermore, in a fifth invention of the present applicationaccording to the fourth invention, the internal end (36) of thedischarge pipe (20) projects inward beyond an inner surface area of thecasing (10).

[0013] Further, in a sixth invention of the present applicationaccording to any one of the first to fifth inventions, the compressionmechanism (15) comprises a fixed scroll (24) and a housing member (23)for housing a movable scroll (26) which matingly engages with the fixedscroll (24), and the housing member (23) is hermetically joined to aninner surface area of the casing (10) over an entire circumferentialperiphery thereof.

[0014] Furthermore, in a seventh invention of the present applicationaccording to the sixth invention, the connection passageway (46) is soformed as to have a transverse cross section shaped like a circular arc.

[0015] Further, in an eighth invention of the present applicationaccording to either the sixth invention or the seventh invention, theconnection passage (46) is so formed as to extend from the fixed scroll(24) to the housing member (23), and fastening apertures (80), forinsertion of bolts (38) for fastening together the fixed scroll (24) andthe housing member (23), are formed in the fixed scroll (24) and thehousing member (23), and the connection passageway (46) and fasteningapertures (80) adjacent to both casing circumferential-direction sidesof the connection passageway (46) respectively are formed such that acenter of a straight line (82) connecting together centers of thefastening apertures (80) lies within the connection passageway (46) in ajoint surface between the fixed scroll (24) and the housing member (23).

[0016] Furthermore, in a ninth invention of the present applicationaccording to the eighth invention, the connection passageway (46) andfastening apertures (80) adjacent to both casingcircumferential-direction sides of the connection passageway (46)respectively are formed such that a center of a straight line (82)connecting together centers of the fastening apertures (80) correspondsto a center (83) of the connection passageway (46) in a joint surfacebetween the fixed scroll (24) and the housing member (23).

WORKING

[0017] In the first invention, working fluid compressed by thecompression mechanism (15) circulates in the connection passageway (46)formed in the compression mechanism (15) and flows out into theclearance space (18) defined between the compression mechanism (15) andthe drive motor (16). At least a part of the working fluid which hasflowed out into the clearance space (18) flows through the motor coolingpassageway (55) between the drive motor (16) and the casing's (10) innersurface and circulates between the clearance space (18) and a side ofthe drive motor (16) which is opposite to the compression mechanism(15), whereby the drive motor (16) is cooled.

[0018] As a result of such arrangement, the drive motor (16) is cooledefficiently by working fluid without increasing the number of componentparts. Besides, it is possible to compactly prepare the compressor (1).Furthermore, problems resulting from forming a working fluid passagewayin a drive shaft, such as a decrease in shaft rigidity and dischargepulsation, will not arise.

[0019] Further, in the second invention according to the firstinvention, working fluid compressed in the compression chamber (40) ofthe compression mechanism (15) passes through the muffler space (45) andthereafter circulates through the connection passageway (46).Accordingly, during the time that working fluid flows into theconnection passageway (46) from the compression chamber (40), operatingnoise is reduced. Therefore, it is possible to provide a compact, lownoise level compressor (1) without increasing the number of componentparts.

[0020] Furthermore, in the third invention according to either the firstinvention or the second invention, working fluid which has flowedthrough the connection passageway (46) and thereafter flowed out intothe clearance space (18) between the compression mechanism (15) and thedrive motor (16) is guided to the motor cooling passageway (55) by theguide plate (58) disposed in the clearance space (18). This ensures thatworking fluid is guided to the motor cooling passageway (55), therebymaking it possible to efficiently cool the drive motor (16) withoutfail.

[0021] Further, in the fourth invention according to the thirdinvention, a part of working fluid which has flowed through theconnection passageway (46) and thereafter flowed out into the clearancespace (18) between the compression mechanism (15) and the drive motor(16), is distributed in a circumferential direction by the flow dividingmeans (90), thereby flowing toward the internal end (36) of thedischarge pipe (20) located in the clearance space (18). The remainingworking fluid flows through the motor cooling passageway (55) betweenthe drive motor (16) which is a DC motor and the casing's (10) innersurface. Accordingly, it is possible to secure cooling of the drivemotor (16) while making improvement in efficiency of separatinglubricant from working fluid, for example when the drive motor (16) oflow temperature rise is employed.

[0022] Furthermore, in the fifth invention according to the fourthinvention, lubricant discharging is controlled. In other words, withregard to working fluid flowing in circumference direction, the closerto the vicinity of the casing's (10) inner surface the higher theconcentration of lubricant becomes. In the fifth invention, since thedischarge pipe (20) projects inward of the casing (10), this makes itpossible to suppress inflow of lubricant and working fluid to thedischarge pipe (20). As a result, it is possible to suppress dischargingof lubricant from the compressor (1).

[0023] Further, in the sixth invention according to any one of the firstto fifth inventions, the housing member (23) is hermetically joined toan inner surface area of the casing (10) over an entire circumferentialperiphery thereof This ensures that the internal space of the casing(10) is divided into the high-level pressure space (28) and thelow-level pressure space (29). Further, it is ensured that both workingfluid leakage and working-fluid suction heating are avoided. And, whilethe fixed scroll (24) and the movable scroll (26) housed in the housingmember (23) are matingly engaging with each other, the compressionmechanism (15) is driven, whereby working fluid is compressed. Theworking fluid thus compressed passes through the connection passageway(46) and is discharged to the high-level pressure space (28).

[0024] Furthermore, in the seventh invention according to the sixthinvention, the connection passageway (46) has a transverse cross sectionshaped like a circular arc. This makes it possible to increase theflowpath area of the connection passageway (46) while suppressingradial-direction expansion of the compression mechanism (15).

[0025] Further, in the eighth invention according to either the sixthinvention or the seventh invention, the connection passageway (46) andfastening apertures (80) adjacent to both casingcircumferential-direction sides of the connection passageway (46) areformed such that a center of a straight line (82) connecting togethercenters of the fastening apertures (80) lies within the connectionpassageway (46) in a joint surface between the fixed scroll (24) and thehousing member (23). This ensures sealing of the fixed scroll (24) andthe housing member (23), thereby preventing leakage of high-pressurefluid in the connection passageway (46) into the low-level pressurespace (29) without fail.

[0026] Furthermore, in the ninth invention according to the eighthinvention, the connection passageway (46) and fastening apertures (80)adjacent to both casing circumferential-direction sides of theconnection passageway (46) are formed such that a center of a straightline (82) connecting together centers of the fastening apertures (80)corresponds to a center (83) of the connection passageway (46) in ajoint surface between the fixed scroll (24) and the housing member (23).This ensures sealing of the fixed scroll (24) and the housing member(23), thereby preventing leakage of high-pressure fluid in theconnection passageway (46) into the low-level pressure space (29)without fail.

EFFECTS OF INVENTION

[0027] In accordance with the first invention, the drive motor (16) iscooled efficiently by working fluid without increasing the number ofcomponent parts. Besides, it is possible to compactly prepare thecompressor (1). Furthermore, problems resulting from forming a workingfluid passageway in a drive shaft, such as a decrease in shaft rigidityand discharge pulsation, will not arise.

[0028] In accordance with the second invention, it is arranged suchthat, during the time that working fluid flows into the connectionpassageway (46) from the compression chamber (40), operating noise isreduced. Therefore, it is possible to provide a compact, low noise levelcompressor (1) without increasing the number of component parts.

[0029] In accordance with the third invention, working fluid is guidedto the motor cooling passageway (55) without fail, thereby ensuring thatthe drive motor (16) is cooled at high efficiency.

[0030] In accordance with the fourth invention, it is possible to securecooling of the drive motor (16) while making improvement in efficiencyof separating lubricant from working fluid, for example when the drivemotor (16) of low temperature rise is employed.

[0031] In accordance with the fifth invention, it is possible tosuppress inflow of lubricant and working fluid into the discharge pipe(20), and it is possible to suppress discharging of lubricant from thecompressor (1).

[0032] In accordance with the sixth invention, the internal space of thecasing (10) is divided into the high-level pressure space (28) and thelow-level pressure space (29) without fail. Both working fluid leakageand working-fluid suction heating are prevented without fail.

[0033] In accordance with the seventh invention, the connectionpassageway (46) has a transverse cross section shaped like a circulararc, thereby making it possible to increase the flowpath area of theconnection passageway (46) while suppressing radial-direction expansionof the compression mechanism (15).

[0034] The eighth and ninth inventions each ensure sealing of the fixedscroll (24) and the housing member (23), thereby preventing leakage ofhigh-pressure fluid in the connection passageway (46) into the low-levelpressure space (29) without fail.

BRIEF DESCRIPTION OF DRAWINGS

[0035]FIG. 1 is a longitudinal sectional view showing an entirearrangement of a high-low pressure dome type compressor according to afirst embodiment of the present invention;

[0036]FIG. 2 is a top plan view showing an upper surface of a fixedscroll;

[0037]FIG. 3 is a top plan view of a covering member;

[0038]FIG. 4 is a top plan view showing an upper surface of a housing;

[0039]FIG. 5 is a partially enlarged view showing a positionalrelationship between fastening apertures and an upper end opening of ascroll side passageway in a fixing part of the housing;

[0040]FIG. 6 shows an entire arrangement of a guide plate in the firstembodiment wherein FIG. 6A is a perspective diagram when viewed from thefront side and FIG. 6B is a perspective diagram when viewed from therear side;

[0041]FIG. 7 is a top plan view of the guide plate in the firstembodiment;

[0042]FIG. 8 is a partially enlarged view showing a positionalrelationship between fastening apertures and an upper end opening of ascroll side passageway in a housing fixing part in a first modificationexample of the first embodiment;

[0043]FIG. 9 is a partially enlarged view showing a positionalrelationship between fastening apertures and an upper end opening of ascroll side passageway in a housing fixing part in a second modificationexample of the first embodiment; and

[0044]FIG. 10 shows an entire arrangement of a guide plate in a secondembodiment of the present invention wherein FIG. 10A is a perspectivediagram when viewed from the front side and FIG. 10B is a perspectivediagram when viewed from the rear side.

BEST MODE FOR CARRYING OUT INVENTION

[0045] Hereinafter, embodiments of the present invention will bedescribed in detail with reference to the drawings.

EMBODIMENT 1

[0046]FIG. 1 shows a high-low pressure dome type compressor (1)according to the present embodiment. The high-low pressure dome typecompressor (1) is connected to a refrigerant circuit (not shown) inwhich refrigerant gas circulates to execute a refrigerating cycle andcompresses refrigerant gas serving as working fluid.

[0047] The compressor (1) of the present embodiment comprises an oblongcylinder-like, hermetically sealed dome type casing (10). The casing(10), made up of a casing main body (11) which is a cylindrical trunkpart having an axis line extending in an up-and-down direction, asaucer-shaped upper wall part (12) which is joined hermetically andintegrally to an upper end of the casing main body (11) by welding andwhich has a convex surface projecting upward, and a saucer-shaped lowerwall part (13) which is joined hermetically and integrally to a lowerend of the casing main body (11) by welding and which has a convexsurface projecting downward, is constructed as a pressure container. Theinterior of the casing (10) is hollow.

[0048] The casing (10) accommodates therein a compression mechanism (15)for compressing refrigerant gas and a drive motor (16) disposed belowthe compression mechanism (15). The compression mechanism (15) and thedrive motor (16) are connected together by a drive shaft (17) which isso disposed as to extend in an up-and-down direction within the casing(10). Defined between the compression mechanism (15) and the drive motor(16) is a clearance space (18).

[0049] The compression mechanism (15) comprises a housing (23) servingas a housing member, a fixed scroll (24) which is so disposed as to befitted closely to an upper part of the housing (23), and a movablescroll (26) which matingly engages with the fixed scroll (24). Thehousing (23) is secured by press fitting to the casing main body (11)over an entire circumferential periphery thereof In other words, thecasing main body (11) and the housing (23) are closely joined togetherover the entire circumferential periphery. And, the internal space ofthe casing (10) is divided into a high-level pressure space (28) belowthe housing (23) and a low-level pressure space (29) above the housing(23). A housing concave portion (31) is formed concavedly in the middleof an upper surface of the housing (23), and a bearing part (32) isformed so as to extend downward from the middle of a lower surface ofthe housing (23). And, a bearing aperture (33) passing through a lowerend surface of the bearing part (32) and a bottom surface of the housingconcave portion (31) is formed in the housing (23), and the drive shaft(17) is inserted rotatably into the bearing aperture (33) through abearing (34).

[0050] A suction pipe (19) for guiding refrigerant in the refrigerantcircuit to the compression mechanism (15) is fitted hermetically to theupper wall part (12) of the casing (10). A discharge pipe (20), throughwhich refrigerant in the casing (10) is discharged outside the casing(10), is fitted hermetically to the casing main body (11). The suctionpipe (19) passes through the low-level pressure space (29) in anup-and-down direction and its internal end is fitted to the fixed scroll(24). Since the suction pipe (19) is so disposed as to pass through thelow-level pressure space (29), this prevents refrigerant from beingheated by refrigerant present in the inside of the casing (10) whenbeing drawn in to the compression mechanism (15) through the suctionpipe (19).

[0051] An internal end (36) of the discharge pipe (20) projects inwardbeyond an inner surface area of the casing (10). And, the internal end(36) of the discharge pipe (20) is formed into a cylindrical shapeextending in an up-and-low direction and is secured firmly to the lowerend of the housing (23). An internal end opening of the discharge pipe(20), i.e., an inflow opening, opens downward. Additionally, the shapeof the internal end (36) of the discharge pipe (20) is not limited to acylindrical shape. For example, the internal end (36) of the dischargepipe (20) may be formed into a triangular shape in longitudinal crosssection which is longer at its lower end in the tip of the dischargepipe (20). In this case, the internal end opening of the discharge pipe(20) opens upward.

[0052] A lower end surface of the fixed scroll (24) is jointed closelyto an upper end surface of the housing (23). The fixed scroll (24) isfastened firmly to the housing (23) by bolts (38).

[0053] The fixed scroll (24) is made up of an end plate (24 a) and aninvolute wrap (24 b) formed in a lower surface of the end plate (24 a).On the other hand, the movable scroll (26) is made up of an end plate(26 a) and an involute wrap (26 b) formed in an upper surface of the endplate (26 a). The movable scroll (26) is supported on the housing (23)through an Oldham ring (39). The upper end of the drive shaft (17) isfitted into the movable scroll (26), and the movable scroll (26) doesnot rotate on its axis but executes an orbital motion within the housing(23) by rotation of the drive shaft (17). The wrap (24 b) of the fixedscroll (24) and the wrap (26 b) of the movable scroll (26) matinglyengage with each other. Between the fixed scroll (24) and the movablescroll (26), a clearance between contacting parts of the wraps (24 b, 26b) becomes a compression chamber (40). The compression chamber (40) isformed such that the volume between the wraps (24 b, 26 b) shrinkstoward the center with the revolution of the movable scroll (26) so thatrefrigerant is compressed.

[0054] Formed in the end plate (24 a) of the fixed scroll (24) are adischarge passageway (41) in communication with the compression chamber(40) and an enlarged concave portion (42) extending to the dischargepassageway (41). The discharge passageway (41) is so formed as to extendin an up-and-down direction in the middle of the end plate (24 a) of thefixed scroll (24). The enlarged concave portion (42) is composed of aconcave portion formed concavedly in an upper surface of the end plate(24 a) and extending in a horizontal direction. A covering member (44)is fastened firmly to the upper surface of the fixed scroll (24) bybolts (44 a) so as to block off the enlarged concave portion (42). And,covering of the enlarged concave portion (42) with the covering member(44) defines a muffler space (45) composed of an expansion chamber forreducing the level of operating noise of the compression mechanism (15).The fixed scroll (24) and the covering member (44) are sealed by closelyjointing them together through a gasket (not shown).

[0055] A connection passageway (46) is formed in the compressionmechanism (15), extending from the fixed scroll (24) to the housing(23). A scroll side passageway (47) notch-formed in the fixed scroll(24) and a housing side passageway (48) notch-formed in the housing (23)communicate with each other, thereby forming the connection passageway(46). An upper end of the connection passageway (46), i.e., an upper endof the scroll side passageway (47), opens to the enlarged concaveportion (42), while a lower end of the connection passageway (46), i.e.,a lower end of the housing side passageway (48), opens to the lower endsurface of the housing (23). In other words, the lower end opening ofthe housing side passageway (48) is a discharge opening (49) throughwhich refrigerant in the connection passageway (46) flows out into theclearance space (18).

[0056] The drive motor (16) is composed of a DC motor comprising anannular stator (51) secured firmly to an internal wall surface area ofthe casing (10) and a rotor (52) rotatably disposed interior to thestator (51). Defined between the stator (51) and the rotor (52) is asmall gap (not shown) extending in an up-and-down direction. This gap isan air gap passageway. Mounted on the stator (51) is a winding, andupper and lower parts of the stator (51) are coil ends (53). The drivemotor (16) is disposed such that an upper end of the upper coil end (53)is substantially flush with a lower end of the bearing (32) of thehousing (23).

[0057] A plurality of core cut parts are notch-formed in areas of anouter peripheral surface of the stator (51), extending from the upperend surface to the lower end surface of the stator (51) at predeterminedcircumferential intervals. By the formation of the core cut parts in theouter peripheral surface of the stator (51), a motor cooling passageway(55) extending in an up-and-down direction is formed between the casingmain body (11) and the stator (51).

[0058] The rotor (52) is drivingly connected to the movable scroll (26)of the compression mechanism (15) through the drive shaft (17) which isso disposed on the axial center of the casing main body (11) as toextend in an up-and-down direction.

[0059] Disposed in the clearance space (18) is a guide plate (58) forguiding refrigerant flowed out of the discharge opening (49) of theconnection passageway (46) to the motor cooling passageway (55). Detailsof the guide plate (58) will be described later.

[0060] Defined below the drive motor (16) is a lower space for holdinglubricant. A centrifugal pump (60) is disposed in the lower space. Thecentrifugal pump (60) is secured firmly to the casing main body (11) andis attached to the lower end of the drive shaft (17). The centrifugalpump (60) draws up lubricant. A lubrication passageway (61) is formedwithin the drive shaft (17), and lubricant drawn up by the centrifugalpump (60) passes through the lubrication passageway (61) and is suppliedto each sliding parts.

[0061] As shown in FIG. 2, the enlarged concave portion (42) of thefixed scroll (24) comprises a central concave portion (64) shaped like acircular when viewed from top and an extendedly-formed concave portion(65) extending radially outwardly from the central concave portion (64).The upper end of the scroll side passageway (47) opens at an outer endof the extendedly-formed concave portion (65), assuming a shape which iselongated relative to a circumferential direction. The periphery of thecentral concave portion (64) and the extendedly-formed concave portion(65) forms the upper end surface of the fixed scroll (24). Formed aroundthe periphery of the central concave portion (64) in the upper endsurface of the fixed scroll (24) are fastening apertures (68) to whichthe bolts (44 a) for fastening and fixing of the covering member (44)are threadedly engaged. Additionally, formed at an outer peripheral endof the fixed scroll (24) are a plurality of fastening apertures (69) towhich the bolts (38) for fastening of the housing (23) to the fixedscroll (24) are threadedly engaged. Two of these fastening apertures(69) are located in the vicinity of the extendedly-formed concaveportion (65).

[0062] Additionally, a suction aperture (66) is formed in the fixedscroll (24). The suction aperture (66) is located in close vicinity tothe extendedly-formed concave portion (65). The upper surface of thefixed scroll (24) and the compression chamber (40) are brought intocommunication with each other by the suction aperture (66). The suctionpipe (19) is fitted into the suction aperture (66). Furthermore, anauxiliary suction aperture (67) is formed adjacent to the suctionaperture (66) in the fixed scroll (24). The low-level pressure space(29) and the compression chamber (40) are brought into communicationwith each other by the auxiliary suction aperture (67).

[0063] As can be seen from FIG. 3, the covering member (44) comprises acircular covering member main body (70) and an extendedly-formed part(71) extending radially outwardly from the covering member main body(70). Formed at an internal side end of the extendedly-formed part (71)is a suction concave portion (72) concavedly formed so as to have acircular arc-like shape with a diameter corresponding to the outsidediameter of the suction pipe (19). Fastening apertures (73), to whichthe bolts (44 a) for fixing of the cover member (44) to the fixed scroll(24) are threadedly engaged, are formed in a peripheral edge of thecovering member main body (70) and in the vicinity of both corners of anouter side end of the extendedly-formed part (71).

[0064] As shown in FIG. 4, formed in the housing concave portion (31) ofthe housing (23) are an outer peripheral concave portion (75) which isformed concavedly from the upper surface so as to extend in acircumferential direction at the outer peripheral end, and a pair ofOldham grooves (76) for fitting of an Oldham ring (39). The Oldhamgrooves (76) are so formed as to face each other. Each Oldham groove(76) is formed into an oval shape.

[0065] An outer peripheral part (78) around the periphery of the housingconcave portion (31) has an upper surface which constitutes the upperend surface of the housing (23) and which is formed joinably to thelower end surface of the fixed scroll (24). In other words, the uppersurface of the outer peripheral part (78) and the lower end surface ofthe fixed scroll (24) are sealed, thereby preventing refrigerant in thehigh-level pressure space (28) from leaking into the low-level pressurespace (29). Formed in the outer peripheral part (78) at predeterminedcircumferential intervals are a plurality of fixing parts (79) extendingradially inwardly. Fastening apertures (80), to which the bolts (38) forfixing of the fixed scroll (24) are threadedly engaged, are formed inthe fixing parts (79). The fastening apertures (80) are formed inpositions corresponding to the fastening apertures (69) formed at theouter peripheral end of the fixed scroll (24).

[0066] Formed in one of the fixing parts (79) is an upper end opening(81) of the housing side passageway (48) constituting the connectionpassageway (46). The upper end opening (81) is shaped like a circulararc which is elongated relative to the casing circumferential direction.Two of the fastening apertures (80) are arrayed in the vicinity of bothcircumferential-direction ends of the upper end opening (81), i.e.,longitudinal-direction ends.

[0067] As shown in FIG. 5, these two fastening apertures (80) arearrayed such that a straight line (82) connecting together the centersof the fastening apertures (80) intersects with a straight line (82a)passing through the center (83) of the upper end opening (81) andextending in a radial direction, at the center (83) of the upper endopening (81). Stated another way, in a joint surface between the fixedscroll (24) and the housing (23), the connection passageway (46) and thefastening apertures (80) adjacent to both casingcircumferential-direction sides of the connection passageway (46)respectively are formed such that the center of the straight line (82)connecting together the centers of the fastening apertures (80)corresponds to the center (83) of the connection passageway (46) (theupper end opening (81) of the housing side passageway (48)).

[0068] The guide plate (58) disposed in the clearance space (18) is madeup of a guide main body (84) and winglike parts (85) disposed at bothends of the guide main body (84), as shown in FIGS. 6 and 7. The guidemain body (84) comprises a lower curved plate (86) having a transversecross section shaped like a circular arc and extending linearly in anup-and-down direction, a protruding part (87) connected to an upper endof the lower curved plate (86) and formed so as to flare more inward ascloser to its upper end, and a side wall part (88) formed verticallytoward the outer peripheral side at both ends of the lower curved plate(86) and the protruding part (87). The lower curved plate (86) isdisposed exterior to the stator (51) of the drive motor (16). The amountof flaring of the protruding part (87) is adjusted such that theprotruding part (87) is located interior to the housing side passageway(48) of the connection passageway (46). In other words, it is arrangedsuch that refrigerant flows, from top down, outside the guide main body(84) of the guide plate (58).

[0069] The winglike part (85) is joined to an outer peripheral side endof the side wall part (88) of the guide main body (84) and is so formedas to have a transverse cross section shaped like a circular arc and toextend linearly in an up-and-down direction. The winglike part (85) isso formed as to have a diameter corresponding to that of the innersurface of the casing main body (11). The winglike part (85) is mountedon the casing main body (11).

[0070] A flow dividing concave portion (90) is formed in the guide plate(58). The flow dividing concave portion (90) constitutes a flow dividingmeans and extends from the winglike part (85) to the side wall part (88)of the guide main body (84). A part of refrigerant flowing to the motorcooling passageway (55) is distributed in a circumferential direction bythe flow dividing concave portion (90) so that it flows toward theinternal end (36) of the discharge pipe (20). The flow dividing concaveportion (90) is so formed as to extend from one of the side ends of thewinglike part (85) to the side wall part (88) jointed to the lowercurved plate (86) of the guide main body (84). The flow dividing concaveportion (90) is a notched concave portion.

[0071] Further, the guide plate (58) is provided with a turn-back part(92) which flares toward the outer peripheral side at the lower end ofthe lower curved plate (86) of the guide plate (84). The tip of theturn-back part (92) is so formed as to be located nearer to the innerperipheral side than the both winglike parts (85). The amount of flaringof the turn-back part (92) is set such that the amount of distributionof refrigerant to the flow dividing concave portion (90) is adjusted toa predetermined ratio.

[0072] Next, the operation of the high-low pressure dome type compressor(1) will be described below.

[0073] In the first place, when the drive motor (16) is activated, therotor (52) starts rotating relative to the stator (51), whereby thedrive shaft (17) rotates. When the drive shaft (17) rotates, the movablescroll (26) does not rotate relative to the fixed scroll (24) butexecutes only an orbital motion. As a result of this, low-pressurerefrigerant is drawn, through the suction pipe (19), into thecompression chamber (40) from the side of a peripheral edge of thecompression chamber (40). With the variation in volume of thecompression chamber (40), the refrigerant is compressed to a high levelpressure. The high-pressure refrigerant is discharged to the mufflerspace (45) from the central part of the compression chamber (40) throughthe discharge passageway (41). Then, the refrigerant flows into theconnection passageway (46) from the muffler space (45), flows throughthe scroll side passageway (47) and the housing side passageway (48),and flows out into the clearance space (18) through the dischargeopening (49).

[0074] The refrigerant in the clearance space (18) flows downwardbetween the guide main body (84) of the guide plate (58) and the innersurface of the casing main body (11), during which time a part of therefrigerant is distributed, passes through the flow dividing concaveportion (90), and flows between the guide plate (58) and the drive motor(16) in a circumferential direction. The refrigerant thus distributedflows in a circumferential direction, so that its lubricant content isseparated. Since the concentration of lubricant is high especially inthe vicinity of the internal wall surface of the casing (10), lubricantseparates well from the refrigerant near the internal wall.

[0075] On the other hand, the refrigerant flowing downward flowsdownward through the motor cooling passageway (55) to the motor lowerspace. And, the refrigerant reverses its flow direction and flows upwardthrough the air gap passageway between the stator (51) and the rotor(52) or through the motor cooling passageway (55) on the opposite side(the left-hand side in FIG. 1) to the connection passageway (46).

[0076] In the clearance space (18), refrigerant which has passed throughthe flow dividing concave portion (90) of the guide plate (58) andrefrigerant which has flowed through the air gap passageway or the motorcooling passageway (55) flow into each other, flow into the dischargepipe (20) from the internal end (36) of the discharge pipe (20), and aredischarged outside the casing (10). And, the refrigerant thus dischargedoutside the casing (10) circulates in the refrigerant circuit and,thereafter, is again drawn, through the suction pipe (19), into thecompressor (1) where the refrigerant is compressed. Such circulation iscarried out repeatedly.

[0077] As has been described, in accordance with the high-low pressuredome type compressor (1) of the first embodiment, refrigerant compressedby the compression mechanism (15) circulates through the connectionpassageway (46) formed in the housing (23) and fixed scroll (24) of thecompression mechanism (15) and flows out into the clearance space (18)between the compression mechanism (15) and the drive motor (16) throughthe discharge opening (49). A part of the refrigerant which has flowedout into the clearance space (18) flows through the motor coolingpassageway (55) between the drive motor (16) and the casing's (10) innersurface and circulates between the clearance space (18) and a side ofthe drive motor (16) which is opposite to the compression mechanism(15), whereby the drive motor (16) is cooled.

[0078] Accordingly, the drive motor (16) is cooled efficiently byrefrigerant without increasing the number of component parts. Besides,it is possible to compactly prepare the compressor (1). Furthermore,problems resulting from forming a working fluid passageway in a driveshaft, such as a decrease in shaft rigidity and discharge pulsation,will not arise.

[0079] Furthermore, refrigerant compressed in the compression chamber(40) of the compression mechanism (15), after passing through themuffler space (45), flows through the connection passageway (46).Accordingly, during the time that refrigerant circulates from thecompression chamber (40) to the connection passageway (46), operatingnoise is reduced. Therefore, it is possible to provide a compact, lownoise level compressor (1) without increasing the number of componentparts.

[0080] Further, refrigerant, which has flowed through the connectionpassageway (46) and flowed out into the clearance space (18) through thedischarge opening (49), is guided to the motor cooling passageway (55)by the guide plate (58) disposed in the clearance space (18). Thisensures that refrigerant is guided to the motor cooling passageway (55),thereby ensuring that the drive motor (16) is cooled efficiently.

[0081] If it is arranged such that all the refrigerant which has flowedout into the clearance space (18) circulates in the motor coolingpassageway (55), this reverses the flow direction of the refrigerant ina lower space of the motor. As a result, the amount of refrigerantflowing upward through the motor cooling passageway (55) increases, andit becomes difficult for lubricant to flow downward through the motorcooling passageway (55). However, if, as in the first embodiment, it isarranged such that the flow of refrigerant is divided and a part thereofis distributed by the flow dividing concave portion (90) of the guideplate (58) disposed in the clearance space (18), this makes it possiblefor lubricant to easily flow downward through the motor coolingpassageway (55).

[0082] Furthermore, a part of refrigerant which has flowed through theconnection passageway (46) and flowed out into the clearance space (18)through the discharge opening (49) is so distributed by the flowdividing concave portion (90) formed in the guide plate (58) as to flowin a circumferential direction while flowing toward the internal end ofthe discharge pipe (20) located in the clearance space (18). Theremaining refrigerant flows through the motor cooling passageway (55)between the drive motor (16) composed of a DC motor and the casing's(10) inner surface. Accordingly, it is possible to secure cooling of thedrive motor (16) of low temperature rise and, at the same time, theefficiency of separation of lubricant contained in refrigerant isimproved by causing the refrigerant to flow in a circumferentialdirection.

[0083] Further, with regard to refrigerant flowing in a circumferencedirection, the closer to the vicinity of the casing's (10) inner surfacethe higher the concentration of lubricant becomes. However, it isarranged such that the internal end (36) of the discharge pipe (20)projects inward beyond the inner surface of the casing main body (11),thereby making it possible to suppress inflow of lubricant into thedischarge pipe (20) together with refrigerant. As a result, it ispossible to suppress discharging of lubricant from the compressor (1)together with refrigerant.

[0084] Furthermore, in the present embodiment, the housing (23) ishermetically joined, at its outer peripheral surface, to the casing mainbody (11) over an entire circumferential periphery thereof This ensuresthat the inside of the casing (10) is divided into the high-levelpressure space (28) and the low-level pressure space (29). Bothrefrigerant leakage and refrigerant suction heating are preventedwithout fail.

[0085] Further, in the present embodiment, the connection passageway(46) has a transverse cross section shaped like a circular arc. Thismakes it possible to increase the flowpath area of the connectionpassageway (46) while suppressing radial-direction expansion of thecompression mechanism (15).

[0086] Furthermore, in the present embodiment, in a joint surfacebetween the fixed scroll (24) and the housing (23), the connectionpassageway (46) and fastening apertures (80) adjacent to both casingcircumferential-direction sides of the connection passageway (46) areformed such that the center of the straight line (82) connectingtogether the centers of the fastening apertures (80) corresponds to thecenter (83) of the connection passageway (46). Such arrangement ensuresthat the fixed scroll (24) and the housing (23) are sealed off from eachother, and high-pressure fluid in the connection passageway (46) isprevented from leaking into the low-level pressure space (29).

MODIFICATION EXAMPLE 1

[0087] In the high-low pressure dome type compressor (1) according tothe first embodiment, of the fastening apertures (80) to which the bolts(38) for fastening of the fixed scroll (24) to the housing (23) arethreadedly engaged, fastening apertures (80) adjacent to both casingcircumferential-direction sides of the connection passageway (46) areformed such that the center of the straight line (82) connectingtogether the centers of the fastening apertures (80) corresponds to thecenter (83) of the connection passageway (46). Alternatively, in a firstmodification example of the first embodiment, it is arranged such thatthe center of the straight line (82) connecting together the centers ofthe fastening apertures (80) lies within the connection passageway (46),as shown in FIG. 8.

[0088] In other words, the upper end opening (81) of the housing sidepassageway (48) constituting the connection passageway (46) is shapedlike a circular arc which is elongated relative to the circumferentialdirection of the casing (10). Besides, the center (83) of the connectionpassageway (46) and each of the centers of the fastening apertures (80)on both casing circumferential-direction sides of the connectionpassageway (46) are so arranged to be lie on the same circumference.And, the straight line (82) connecting together the centers of thefastening apertures (80) adjacent to both circumferential sides of theupper end opening (81) and the straight line (82 a) passing through thecenter (83) of the connection passageway (46) (the center (83) of theupper end opening (81)) and extending in a radial direction intersectwith each other within the upper end opening (81).

[0089] Stated another way, the upper end opening (81) of the housingside passageway (48) constituting the connection passageway (46) isshaped like a circular arc having such a circumferential length that thedistance between two fastening apertures (80) adjacent to both casingcircumferential-direction sides of the upper end opening (81) does notexpand excessively. That is to say, in order to gain refrigerant flowrate, it is desirable that the circumferential length of the connectionpassageway (46) is extended. However, if extended too much, the distancebetween the fastening apertures (80) will expand excessively, and thereis a worry that sealability falls. To cope with this, the connectionpassageway (46) and the fastening apertures (80) are formed such thatthe center of the straight line (82) connecting together the centers oftwo fastening apertures (80) adjacent to both sides of the upper endopening (81) lies in the inside of the connection passageway (46) (i.e.,in the inside of the upper end opening (81) of the housing sidepassageway (48)).

[0090] Even when the connection passageway (46) and the fasteningapertures (80) are formed in the way as described above, airtightnessbetween the fixed scroll (24) and the housing (23) is maintained.Furthermore, sealing between the high-level pressure space (28) and thelow-level pressure space (29) is ensured, thereby preventing leakage ofhigh-pressure refrigerant in the connection passageway (46) to thelow-level pressure space (29) without fail. Other arrangements, working,and effects are the same as stated in the first embodiment.

MODIFICATION EXAMPLE 2

[0091] In a second modification example of the first embodiment, theconnection passageway (46) and the fastening apertures (80) are formedemploying a different arrangement from the first modification example inthat the center of the straight line (82) connecting together thecenters of the fastening apertures (80) lies at a radial-directioninternal end of the connection passageway (46), as shown in FIG. 9.

[0092] To sum up, the upper end opening (81) of the housing sidepassageway (48) constituting the connection passageway (46) is shapedlike a circular arc which is elongated relative to the circumferentialdirection of the casing (10). Furthermore, the center (83) of theconnection passageway (46) and each of the centers of the fasteningapertures (80) adjacent to both casing circumferential-direction sidesof the connection passageway (46) are so arranged as to lie on the samecircumference. And, the straight line (82) connecting together thecenters of the fastening apertures (80) adjacent to the bothcircumferential-direction sides of the upper end opening (81) and thestraight line (82 a) passing through the center (83) of the connectionpassageway (46) (the center (83) of the upper end opening (81)) andextending in a radial direction intersect with each other at aradial-direction internal end of the connection passageway (46) (i.e.,the upper end opening (81) of the housing side passageway (48)) so as tocome into contact with the upper end opening (81).

[0093] Even when the connection passageway (46) and the fasteningapertures (80) are formed in the way as described above, airtightnessbetween the fixed scroll (24) and the housing (23) is maintained.Furthermore, sealing between the high-level pressure space (28) and thelow-level pressure space (29) is ensured, thereby preventing leakage ofhigh-pressure refrigerant in the connection passageway (46) to thelow-level pressure space (29) without fail. Other arrangements, working,and effects are the same as stated in the first embodiment.

EMBODIMENT 2

[0094] In the guide plate (58) disposed in the high-low pressure dometype compressor (1) according to a second embodiment of the presentinvention, the provision of the flow dividing concave portion (90) isomitted, as shown in FIG. 10. Here, the same reference numerals havebeen applied to the same component parts as in the first embodiment andtheir description is omitted.

[0095] More specifically, the guide plate (58) of the second embodimentis comprised of the guide main body (84) and the winglike parts (85)disposed at both ends of the guide main body (84). The guide main body(84) comprises the lower curved plate (86) having a transverse crosssection shaped like a circular arc and extending linearly in an up-anddown direction and the protruding part (87) connected to an upper end ofthe lower curved plate (86) and formed so as to flare more toward theinner periphery as closer to its upper end, and the side wall part (88)formed vertically toward the outer peripheral side at both ends of thelower curved plate (86) and the protruding part (87).

[0096] The winglike parts (85) are joined to outer peripheral side endsof the side wall part (88) of the guide main body (84) and are so formedas to have a transverse cross section shaped like a circular arc and toextend linearly in an up-and-down direction. Unlike the firstembodiment, in the winglike part (85) of the second embodiment its lowerend is positioned at an intermediate height of the lower curved plate(86) of the guide main body (84).

[0097] The drive motor (16) is formed for example by an induction motor.

[0098] Accordingly, refrigerant, which has flowed through the connectionpassageway (46) and flowed out into the clearance space (18) from thedischarge opening (49), flows downward between the guide main body (84)of the guide plate (58) and the inner surface of the casing main body(11). And, all the refrigerant flows downward through the motor coolingpassageway (55) to a lower space of the motor where its flow directionis reversed. Then, the refrigerant flows upward through an air gappassageway between the stator (51) and the rotor (52) or through themotor cooling passageway (55) opposite to the connection passageway(46). Thereafter, the refrigerant flows into the discharge pipe (20)from the internal end (36) of the discharge pipe (20) and is dischargedoutside the casing (10).

[0099] In accordance with the high-low pressure dome type compressor (1)of the second embodiment, it is arranged such that all the refrigerantwhich has flowed out into the clearance space (18) flows into the motorcooling passageway (55). As a result of such arrangement, the drivemotor (16) is cooled efficiently without fail in comparison with thehigh-low pressure dome type compressor (1) according to the firstembodiment.

[0100] Other arrangements, working, and effects are the same as in thefirst embodiment.

OTHER EMBODIMENTS

[0101] As to the foregoing embodiments, the compression mechanism (15)is not limited to a scroll type. For example, the compression mechanism(15) may be formed into a rotary piston type.

[0102] Further, as to the foregoing embodiments, the muffler space (45)in the compression mechanism (15) may be omitted.

[0103] Furthermore, as to first embodiment, the guide plate (58) may beomitted. Moreover, as to the first embodiment, the drive motor (16) isnot limited to a DC motor. The drive motor (16) may be implemented by anAC motor.

[0104] Besides, as to the second embodiment, the internal end (36) ofthe discharge pipe (20) is not limited to the foregoing construction inwhich it projects inward beyond the inner surface of the casing mainbody (11).

[0105] Moreover, in each of the foregoing embodiments the connectionpassageway (46) has a transverse cross section shaped like a circulararc which is elongated relative to the circumferential direction of thecasing. Alternatively, the connection passageway (46) may have acircular transverse cross section.

INDUSTRIAL APPLICABILITY

[0106] As has been described above, the present invention provides ahigh-low pressure dome type compressor which is useful when employed ina refrigerant circuit or the like, particularly when disposed in a smallspace.

1. A high-low pressure dome type compressor of comprising: a casinghaving a compression mechanism and an internal space that is dividedinto high-level and low-level pressure spaces and facing each otheracross said compression mechanism; a drive motor drivingly connected tosaid compression mechanism and disposed in said high-level pressurespace; a connection passageway formed in said compression mechanism,through which working fluid compressed in a compression chamber of saidcompression mechanism flows out into a clearance space defined betweensaid compression mechanism and said drive motor; and a motor coolingpassageway formed between said drive motor and an inner surface area ofsaid casing, through which working fluid which has flowed out of saidconnection passageway circulates between said clearance space and a sideof said drive motor which is opposite to said compression mechanism 2.The high-low pressure dome type compressor of claim 1, wherein saidcompression mechanism is provided with a muffler space which is formedbetween said compression chamber and said connection passageway.
 3. Thehigh-low pressure dome type compressor of claim 1, further comprising aguide plate that is disposed in said clearance space, and configured toguide working fluid which has flowed out of said connection passagewayto said motor cooling passageway.
 4. The high-low pressure dome typecompressor of claim 3, wherein said casing is provided with a dischargepipe through which working fluid in said high-level pressure space isdischarged outside said casing, and said guide plate is provided with aflow dividing portion configured to distribute a part of working fluidflowing toward said motor cooling passageway in a circumferentialdirection and guide said distributed working fluid to an internal end ofsaid discharge pipe that is located in said clearance space.
 5. Thehigh-low pressure dome type compressor of claim 4, wherein said internalend of said discharge pipe projects inward beyond an inner surface areaof said casing.
 6. The high-low pressure dome type compressor of claims1, wherein said compression mechanism comprises a fixed scroll and ahousing member that houses a movable scroll which matingly engages withsaid fixed scroll, and said housing member is hermetically joined to aninner surface area of said casing over an entire circumferentialperiphery thereof.
 7. The high-low pressure dome type compressor ofclaim 6, wherein said connection passageway is so formed as to have atransverse cross section shaped like a circular arc.
 8. The high-lowpressure dome type compressor of claim 6, wherein said connectionpassageway is so formed as to extend from said fixed scroll to saidhousing member, said fixed scroll and said housing member having atleast first and second fastening apertures, with bolts disposed thereinthat fasten said fixed scroll and said housing member together, areformed in said and said connection passageway and said first and secondfastening apertures that are adjacent to first and second casingcircumferential-direction sides of said connection passageway,respectively, are formed such that a center of a straight lineconnecting together centers of said first and second fastening apertureslies within said connection passageway in a joint surface between saidfixed scroll and said housing member.
 9. The high-low pressure dome typecompressor of claim 8, wherein said connection passageway and said firstand second fastening apertures adjacent to said first and second casingcircumferential-direction sides of said connection passageway,respectively, are formed such that the center of the straight lineconnecting together the centers of said first and second fasteningapertures corresponds to a center of said connection passageway in saidjoint surface between said fixed scroll and said housing member.
 10. Thehigh-low pressure dome type compressor of claim 2, further comprising aguide plate that is disposed in said clearance space and configured toguide working fluid which has flowed out of said connection passagewayto said motor cooling passageway.
 11. The high-low pressure dome typecompressor of claim 10, wherein said casing is provided with a dischargepipe through which working fluid in said high-level pressure space isdischarged outside said casing, and said guide plate is provided with aflow dividing portion configured to distribute a part of working fluidflowing toward said motor cooling passageway in a circumferentialdirection and guide said distributed working fluid to an internal end ofsaid discharge pipe that is located in said clearance space.
 12. Thehigh-low pressure dome type compressor of claim 11, wherein saidinternal end of said discharge pipe projects inward beyond an innersurface area of said casing.
 13. The high-low pressure dome typecompressor of claim 12, wherein said compression mechanism comprises afixed scroll and a housing member that houses a movable scroll whichmatingly engages with said fixed scroll, and said housing member ishermetically joined to an inner surface area of said casing over anentire circumferential periphery thereof.
 14. The high-low pressure dometype compressor of claim 13, wherein said connection passageway is soformed as to have a transverse cross section shaped like a circular arc.15. The high-low pressure dome type compressor of claim 14, wherein saidconnection passageway is so formed as to extend from said fixed scrollto said housing member, said fixed scroll and said housing member havingat least first and second fastening apertures with bolts disposedtherein that fasten said fixed scroll and said housing member together,and said connection passageway and said first and second fasteningapertures that are adjacent to first and second casingcircumferential-direction sides of said connection passageway,respectively, are formed such that a center of a straight lineconnecting together centers of said first and second fastening apertureslies within said connection passageway in a joint surface between saidfixed scroll and said housing member.
 16. The high-low pressure dometype compressor of claim 15, wherein said connection passageway and saidfirst and second fastening apertures adjacent to said first and secondcasing circumferential-direction sides of said connection passageway,respectively, are formed such that the center of the straight lineconnecting together the centers of said first and second fasteningapertures corresponds to a center of said connection passageway in saidjoint surface between said fixed scroll and said housing member.
 17. Thehigh-low pressure dome type compressor of claim 2, wherein saidcompression mechanism comprises a fixed scroll and a housing member thathouses a movable scroll which matingly engages with said fixed scroll,and said housing member is hermetically joined to an inner surface areaof said casing over an entire circumferential periphery thereof.
 18. Thehigh-low pressure dome type compressor of claim 3, wherein saidcompression mechanism comprises a fixed scroll and a housing member thathouses a movable scroll which matingly engages with said fixed scroll,and said housing member is hermetically joined to an inner surface areaof said casing over an entire circumferential periphery thereof.
 19. Thehigh-low pressure dome type compressor of claim 18, wherein saidconnection passageway is so formed as to extend from said fixed scrollto said housing member, said fixed scroll and said housing member havingat least first and second fastening apertures with bolts disposedtherein that fasten said fixed scroll and said housing member together,and said connection passageway and said first and second fasteningapertures that are adjacent to first and second casingcircumferential-direction sides of said connection passageway,respectively, are formed such that a center of a straight lineconnecting together centers of said first and second fastening apertureslies within said connection passageway in a joint surface between saidfixed scroll and said housing member.
 20. The high-low pressure dometype compressor of claim 19, wherein said connection passageway and saidfirst and second fastening apertures adjacent to said first and secondcasing circumferential-direction sides of said connection passageway,respectively, are formed such that the center of the straight lineconnecting together the centers of said first and second fasteningapertures corresponds to a center of said connection passageway in saidjoint surface between said fixed scroll and said housing member.